1. Field of the Invention
The present invention relates to apparatus and methods for transferring products from a storage/transport vehicle to a work station. In particular, the invention relates to apparatus and methods for unloading, at high speed, a large quantity of products, such as empty plastic containers or bottles, stacked in tiers on the pallet.
2. Prior Art
Apparatus which fills empty bottles and/or containers at an high production rate require a large quantity of empty bottles or containers for continuous operation. High speed apparatus has been developed for securing and orienting empty bottles or containers stored in a hopper or bin. Such apparatus uses large quantities of empty bottles or containers, in short periods of time. An example of patents that teaches high speed container positioning and orienting apparatus are the U.S. Pat. No. 4,681,209, issued to Marti in July 1987 and the U.S. Pat. No. 5,415,322, issued to Sala in May 1995. The teachings in these patents include the automatic securing, positioning and aligning of each of a large quantity of empty bottles or containers, such as plastic bottles or containers, for example, on a bottle-by-bottle basis, at an high speed. In order that this type of high speed apparatus operate continuously, a large quantity of empty bottles or containers need be fed to the apparatus. In practice, large quantities of empty bottles are loaded on to pallets, in stacks of tiers and are transported, by fork-lift or other vehicle, for example, to the high speed bottle or container unloading apparatus.
The tiers defining the stack on the pallet normally include a tier or support sheet on which a quantity of containers are aligned, utilizing the upper surface of the tier or support sheet. Depending upon the size of the bottles or containers, a tier of plastic bottles, for example, may include as many as 200 to 300 plastic bottles. The pallet is stacked with as many tiers as practical, considering the size of the bottle or container stored in the stack. If, for example, the bottles or containers are six (6) to ten (10) inches in height, the stack may include as many as eight (8) to eleven ( 11) tiers. The stacking or cascading of so many tiers on a four foot by four foot pallet makes a relatively unstable package or load. Also, bottles or containers of such size, especially empty, plastic bottles, are very light in weight, further increasing the instability of the load. In order to stabilize the load, the stack on the pallet is wrapped with a plastic or paper wrap or sheeting and/or is often banded with bands or straps. The sheeting wrap closely envelopes the stack so that the wrapping both supports the stack and keeps empty containers clean during shipping and/or storage. Bands, which may also be used, further secure the load to the pallet and support and stabilize the load on the pallet. The bands may extend longitudinally about or over the load on the pallet. The bands used to secure the load are often secured to or extended about the pallet thus tying the load to the pallet providing additional support. Stabilizing the load in this manner is effective, inexpensive and practical and is in common use in the field. However, the problems of removing the sheeting and the bands or straps from the stack are not addressed in the prior art.
Apparatus for unloading pallets stacked with bottles or containers is the subject of several U.S. patents. Examples of U.S. patents which teach apparatus for unloading a pallet stacked with tiers of products, such as cartons, cases, bottles or containers are:
#3,543,949 to Weier 1970; #3,724,686 to Nelson 1973; #4,037,734 to Erdman 1977; #4,527,930 to Biery 1985; #5,033,929 to Marti 1991.
The patents to Weier ('949); to Nelson ('686); to Biery ('940); and to Marti ('929) each teach apparatus for incrementally elevating the pallet and the stack of tiers loaded on the pallet. As the pallet and load on the pallet are incrementally raised, each top tier is removed from the stacked load. Removal of the tier is accomplished at a particular level or work zone in the apparatus. When the tier enters the work zone, each tier is individually unloaded from the stack by a product handling apparatus. Each of the above identified U.S. patents teach apparatus for unloading a pallet on a tier-by-tier basis. The presence and the removal of the sheet wrapping from around the stack is not addressed. The presence and removal of the bands from around the stack are not addressed, and the presence and removal of the tier sheets defining the stack, are not mentioned or addressed in any of the above mentioned U.S. patents. Erdman ('734) teaches a speciality apparatus for unloading tiers of cases of bottles, stacked on a pallet, where a case defines a tier in the stack. The cases in the stack are oriented so that the opening of each case is at the bottom of the case in the stack. Erdman teaches inverting each case as it is removed from the stack of cases. The pallet, loaded with inverted cases containing bottles, is placed in a flat frame and the flat frame, the pallet and the stack are pivoted so that the pallet and the stack are rotated from a vertical orientation to an horizontal orientation. Erdman teaches removing each case from the horizontally laid stack of cases on a case-by-case, or tier-by-tier, basis. Marti ('929), while teaching tier-by-tier handling of a stack of tiers, with incremental stack elevation, also teaches a special construction for the tier sheet, with apparatus for securing and pivoting the upper most tier on the stack, so that the products supported by one specially constructed tier sheet are dumped into a hopper or a bin on a tier-by-tier basis. Marti ('929) is limited, requiring a specially constructed tier sheet, without which the teaching does not appear to be practical.
In summary, the prior art addresses the problem of unloading products stored in a stack of tiers, stacked on a pallet on a tier-by-tier basis, effectively maintaining the integrity of the stack of tiers during unloading. The efficiency of the prior art leaves much to be desired. The present invention addresses the problem of unloading products stored in a stack of tiers stacked on a pallet by providing a movable holding chamber for securing the pallet and stack of tiers, apparatus for destroying the stack of tiers held in the holding chamber for releasing the products from the stack environment, and apparatus for delivering the products previously held in the stack, for efficient, high speed unloading of products stacked in tiers, on a pallet.